Extractor piping on outermost sidewall of immersion hood apparatus

ABSTRACT

In some embodiments, the present disclosure relates to a process tool that includes a lithography apparatus arranged over a wafer chuck and an immersion hood apparatus laterally around the lithography apparatus. The lithography apparatus includes a photomask arranged between a light source and a lens. The immersion hood apparatus comprises input piping, output piping, and extractor piping. The input piping is arranged on a lower surface of the immersion hood apparatus and configured to distribute a liquid between the lens and the wafer chuck. The output piping is arranged on the lower surface of the immersion hood apparatus and configured to contain the liquid arranged between the lens and the wafer chuck. The extractor piping is arranged on an outer sidewall of the immersion hood apparatus and configured to remove any liquid above the wafer chuck that is outside of the immersion hood apparatus.

BACKGROUND

Integrated chips are fabricated in semiconductor fabrication facilities.Fabrication facilities contain processing tools that are configured toperform processing steps (e.g., etching steps, photolithography steps,deposition steps, etc.) upon a substrate. Lithography is a commonly usedfabrication process by which a photomask having a pattern is irradiatedwith electromagnetic radiation through a series of lenses to transferthe pattern onto a photosensitive material overlying a substrate.Selective parts of the substrate may be subsequently processed accordingto the patterned photosensitive material.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates a cross-sectional view of some embodiments of animmersion hood apparatus comprising extractor piping on outermostsidewalls of the immersion hood apparatus configured to remove residualwater from a semiconductor substrate.

FIG. 2 illustrates a top-view of some embodiments of an immersion hoodapparatus comprising extractor piping arranged on outermost sidewalls ofthe immersion hood apparatus configured to remove residual water from asemiconductor substrate.

FIGS. 3 and 4 illustrate perspective views of some embodiments of anoutermost sidewall of an immersion hood apparatus that comprisesextractor piping.

FIG. 5 illustrates a cross-sectional view of some embodiments of alithography apparatus comprising a lens, light source, and photomaskthat is surrounded by an immersion hood apparatus comprising extractorpiping on outermost sidewalls of the immersion hood apparatus.

FIGS. 6-15 illustrate cross-sectional views of some embodiments of amethod of performing immersion lithography using an immersion hoodapparatus, wherein the immersion hood apparatus comprises extractorpiping on outermost sidewalls of the immersion hood apparatus configuredto remove residual water from a semiconductor substrate.

FIG. 16 illustrates a flow diagram of some embodiments of the methodcorresponding to FIGS. 6-15 .

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Instead of using air as in dry photolithography, immersion lithographyuses a liquid between a bottommost lens and a photosensitive layer toincrease the resolution of a solubility pattern transferred from aphotomask to the photosensitive layer. The resolution of the solubilitypattern transferred onto the photosensitive layer is related to therefractive index of the liquid used in the immersion lithographyprocess. Oftentimes, the liquid used in immersion lithography has arefractive index greater than 1, such as water, for example. Thephotosensitive layer may be arranged over a semiconductor substrate, andvarious features are formed on or within the semiconductor substratebased on the solubility pattern transferred from the photomask to thephotosensitive layer. Thus, the higher the resolution achieved by theimmersion lithography process, the smaller the size of the featuresformed on or within the semiconductor substrate may be. By reducing thesize of features and/or the space between features formed on or within asemiconductor substrate, the size of the overall device is reduced.

In immersion lithography, an immersion hood apparatus may comprise inputpiping used to inject water and output piping used to contain water onan immersion area of the semiconductor substrate. A lithographyapparatus comprising a series of lenses, a photomask, and a light sourcemay be arranged over the immersion hood apparatus and are configured todirect light onto the immersion area of the semiconductor substrate. Theimmersion hood apparatus and the lithography apparatus may staystationary as the semiconductor substrate is moved around such that thepattern is transferred to the total desired area of the photosensitivelayer on the semiconductor substrate.

However, in some embodiments, as the semiconductor substrate is movedaround, residual liquid (e.g., water) may be left behind on thesemiconductor substrate and does not get removed from the semiconductorsubstrate by the output piping of the immersion hood apparatus. Theresidual liquid (e.g., water) may damage features on the semiconductorsubstrate and/or negatively interfere with future processing steps.

Various embodiments of the present disclosure relate to an immersionhood apparatus comprising the input and output piping, as well asextractor piping on outermost sidewalls of the immersion hood apparatus.The extractor piping is configured to remove residual liquid left behindon areas of the semiconductor substrate. In some embodiments, theextractor piping is arranged at an angle favorable to remove theresidual liquid up and away from the semiconductor substrate. Byreducing or even eliminating residual liquid left behind by immersionlithography, the extractor piping on the outermost sidewalls of theimmersion hood apparatus mitigates damage to and increases reliabilityof features on the semiconductor substrate.

FIG. 1 illustrates a cross-sectional view 100 of some embodiments of animmersion hood apparatus comprising extractor piping.

The cross-sectional view 100 of FIG. 1 illustrates an immersion hoodapparatus 106 arranged over a wafer chuck 102. In some embodiments, theimmersion hood apparatus 106 comprises an opening 116, and a lithographyapparatus 118 is arranged over the immersion hood apparatus 106 and theopening 116. In some embodiments, the lithography apparatus 118comprises one or more lenses, a light source, and a photomask betweenthe light source and the one or more lenses. In some embodiments, thewafer chuck 102 is configured to hold a semiconductor substrate 104,which may be or comprise a semiconductor wafer. Further, in someembodiments, a photosensitive layer 105 is arranged over thesemiconductor substrate 104.

In some embodiments, the immersion hood apparatus 106 comprises inputpiping 108 configured to inject a liquid 114 between a bottommostsurface 118 b of the lithography apparatus 118 and portions of the waferchuck 102 and the photosensitive layer 105 arranged directly below theopening 116 of the immersion hood apparatus 106. In some embodiments,the liquid 114 naturally spreads outwards, away from the opening 116 andthe input piping 108 of the immersion hood apparatus 106. Thus, in someembodiments, the immersion hood apparatus 106 further comprises outputpiping 110 configured to remove the liquid 114 that travels away fromthe opening 116 and the input piping 108 of the immersion hood apparatus106. In other words, the output piping 110 is configured to contain theliquid 114 to an immersion area over the wafer chuck 102 defined by aperimeter of the output piping 110. In some embodiments, the inputpiping 108 and the output piping 110 are arranged on a lower surface ofthe immersion hood apparatus 106.

During operation, an immersion lithography process is performed, whereinlight from the light source in the lithography apparatus 118 is directedthrough the photomask and the one or more lenses to change a solubilityof portions of the photosensitive layer 105 according to the photomask.Because of the liquid 114 arranged between the lithography apparatus 118and the photosensitive layer 105, the light also travels through theliquid 114. In some embodiments, the liquid 114 has a refractive indexgreater than 1. In some embodiments, the liquid 114, may comprise, forexample, water. The liquid 114 increases the resolution of the lightthat reaches the photosensitive layer 105 according to the photomask,thereby reducing the sizes of features formed on the photosensitivelayer 105 and/or the semiconductor substrate 104 based on the immersionlithography process. In some embodiments, the wafer chuck 102 isconfigured to move and to hold onto the semiconductor substrate 104while moving such that the immersion lithography process may beconducted on the entire area of the photosensitive layer 105. Then, insome embodiments, the photosensitive layer 105 may be developed, orexposed to a wet etchant, to remove soluble portions of thephotosensitive layer 105 as defined by the photomask and immersionlithography process.

In some embodiments, the immersion hood apparatus 106 further comprisesextractor piping 112 arranged on outermost sidewalls 106 s of theimmersion hood apparatus 106. The extractor piping 112 is configured toremove residual liquid that escapes from between the immersion hoodapparatus 106 and the wafer chuck 102 as the wafer chuck 102 movesduring the immersion lithography process. In some embodiments, theextractor piping 112 comprises a lower segment 112L that extends fromthe outermost sidewalls 106 s and towards the opening 116 of theimmersion hood apparatus and comprises an upper segment 112U thatextends from the lower segment 112L and vertically away from the waferchuck 102. The lower segment 112L of the extractor piping 112 iscontinuously connected to the upper segment 112U of the extractor piping112.

In some embodiments, the lower segment 112L meets the upper segment 112Uat a first angle A₁ measured on a side of the extractor piping 112 thatis closest to the outermost sidewalls 106 s of the immersion hoodapparatus 106. In some embodiments, the first angle A₁ is an obtuseangle, and thus, is greater than 90 degrees. In some embodiments, thelower segment 112L of the extractor piping 112 is arranged at a secondangle A₂ with respect to the lower surface of the immersion hoodapparatus 106. In some embodiments, the second angle A₂ is an acuteangle, and thus, is less than 90 degrees. In such embodiments, thesomewhat horizontal and somewhat vertical lower segment 112L of theextractor piping 112 increases the effectiveness of the extractor piping112 of removing residual liquid up and away from the photosensitivelayer 105. In some embodiments, the upper segment 112U is arranged at asubstantially right angle with respect to the lower surface of theimmersion hood apparatus 106.

Further, in some embodiments, the lower segment 112L of the extractorpiping 112 has a first diameter d₁, and the upper segment 112U of theextractor piping 112 has a second diameter d₂. In some embodiments, thefirst and second diameter d₁, d₂ are each in a range of between, forexample, approximately 0.05 millimeters and approximately 100millimeters. In some embodiments, if the first or second diameters d₁,d₂ are less than 0.05 millimeters, the extractor piping 112 may be toosmall to remove the liquid 114. In some embodiments, the second diameterd₂ is greater than or equal to the first diameter d₁. Accordingly, insome embodiments, pressure or exhaust velocity in the lower segment 112Lof the extractor piping 112 is equal to or greater than pressure orexhaust velocity in the upper segment 112U of the extractor piping 112.This way, residual liquid that is not arranged directly between theimmersion hood apparatus 106 and the wafer chuck 102 may be effectivelyremoved by the extractor piping 112 to reduce defects cause by residualliquid over the photosensitive layer 105 as the immersion lithographyprocess is conducted.

FIG. 2 illustrates a top-view 200 of some embodiment of an immersionhood apparatus arranged over a semiconductor substrate.

In some embodiments, the immersion hood apparatus 106 has an overallsquare-like shape from the top-view 200. In some other embodiments, theimmersion hood apparatus 106 may have an overall rectangular-like shape,circular-like shape, or some other shape from the top-view 200. In someembodiments, the input piping 108 and the output piping 110 of theimmersion hood apparatus 106 may each comprise multiple pipes havingopenings spaced apart from one another. In some embodiments, theextractor piping 112 may comprise a continuous opening around theperimeter of the immersion hood apparatus 106. In some otherembodiments, the extractor piping 112 may comprise multiple pipes havingopenings 202 spaced apart from one another. In some embodiments, theopenings 202 are actually arranged on the outermost sidewall 106 s ofthe immersion hood apparatus 106, and thus, are illustrated with dottedlines in the top-view 200 of FIG. 2 . In some embodiments, the openings202 of each pipe of the extractor piping 112 may have the first diameterd₁.

Further, in some embodiments, an inner perimeter of the immersion hoodapparatus 106 may be defined by the opening 116 in the immersion hoodapparatus 106. In some embodiments, the opening 116 may have an overallsquare-like shape from the top-view 200, whereas in other embodiments,the opening 116 may have an overall rectangular-like shape,circular-like shape, or some other shape from the top-view 200.

In some embodiments, during parts of the immersion lithography process,the immersion hood apparatus 106 may completely and directly overlie thesemiconductor substrate 104, whereas during other parts of the immersionlithography process, the immersion hood apparatus 106 may only partiallyand directly overlie the semiconductor substrate 104. Thus, in someembodiments and/or during some times of the immersion lithographyprocess, the extractor piping 112 completely overlies the semiconductorsubstrate 104, whereas in other embodiments and/or during other times ofthe immersion lithography process, only some of the extractor piping 112directly overlies the semiconductor substrate 104. Nevertheless, in someembodiments, the extractor piping 112 is arranged at the outer perimeterof the immersion hood apparatus 106 on the outermost sidewalls 106 s ofthe immersion hood apparatus 106 to remove any residual liquid arrangedon portions of the photosensitive layer 105 that are not arrangeddirectly between the immersion hood apparatus 106 and the semiconductorsubstrate 104 or that are not arranged directly between the opening 116of the immersion hood apparatus 106 and the semiconductor substrate 104.

FIG. 3 illustrates a perspective view 300 of some embodiments of anouter sidewall of a portion of an immersion hood apparatus comprisingextractor piping.

In some embodiments, as in the perspective view 300 of FIG. 3 , theextractor piping 112 comprises a continuous pipe and opening 302 on theoutermost sidewalls 106 s of the immersion hood apparatus 106.

FIG. 4 illustrates a perspective view 400 of some other embodiments ofan outer sidewall of a portion of an immersion hood apparatus comprisingextractor piping.

In some embodiments, as in the perspective view 400 of FIG. 4 , theextractor piping 112 comprises multiple pipes with openings 202 on theoutermost sidewalls 106 s of the immersion hood apparatus 106. In suchembodiments, the exhaust force or the exhaust velocity of each pipe ofthe extractor piping 112 is greater than the exhaust force or theexhaust velocity of the continuous pipe and opening (302 of FIG. 3 ) asillustrated in the embodiment of FIG. 3 . Thus, in some embodiments, theextractor piping 112 comprising multiple pipes with openings 202 asillustrated in FIG. 4 has a higher exhaust velocity and thus, is moreeffective in removing residual water from the photosensitive layer (105of FIG. 1 ) during the immersion lithography process than extractorpiping 112 that comprises a continuous pipe as illustrated in FIG. 3 .

FIG. 5 illustrates a cross-sectional view 500 of some embodiments of animmersion hood apparatus and a lithography apparatus configured topattern a first area of an underlying photosensitive layer.

In some embodiments, the lithography apparatus 118 comprises a lightsource 510 configured to apply light/electromagnetic radiation towardsthe photosensitive layer 105 beneath the opening 116 in the immersionhood apparatus 106. In some embodiments, the light source 510 isconfigured to apply light having a wavelength in a range of between, forexample, approximately 175 nanometers and approximately 200 nanometers.In some embodiments, the lithography apparatus 118 further comprises aphotomask 508 arranged below the light source 510. The photomask 508 maycomprise a solubility pattern having portions that allow light to passthrough and other portions that do not allow light to pass through. Thelight that passes through the photomask 508 changes the solubility ofthe photosensitive layer 105. Further, in some embodiments, a series oflenses, such as, a first lens 502, a second lens 504 arranged over thefirst lens 502, and a third lens 506 arranged over the second lens 504,are arranged between the bottommost surface 118 b of the lithographyapparatus 118 and the photomask 508. In some embodiments, the first,second, and third lenses 502, 504, 506 focus the light from the lightsource 510 that travels through the photomask 508 towards a first area512 on the photosensitive layer 105. In some embodiments, the first,second, and third lenses 502, 504, 506 are used because the photomask508 is larger than the desired solubility pattern to be transferred ontothe first area 512 of the photosensitive layer 105. Thus, between thefirst lens 502, the second lens 504, the third lens 506, and/or theliquid 114, the solubility pattern defined by the photomask 508 isreduced in size and transferred onto the first area 512 of thephotosensitive layer 105 with a high resolution.

In some embodiments, the liquid 114 is arranged between the bottommostlens (i.e., the first lens 502) and the first area 512 of thephotosensitive layer 105. In some embodiments, when light travelsthrough the liquid 114 instead of, for example, air, the resolution ofthe light and thus, the solubility pattern transferred from thephotomask 508 to the first area 512 of the photosensitive layer 105 isincreased.

FIGS. 6-15 illustrate various views 600-1500 of some embodiments of amethod of conducting an immersion lithography process, wherein extractorpiping on outermost sidewalls of an immersion hood apparatus removesresidual water as the immersion lithography process is conducted ondifferent areas over a semiconductor substrate. Although FIGS. 6-15 aredescribed in relation to a method, it will be appreciated that thestructures disclosed in FIGS. 6-15 are not limited to such a method, butinstead may stand alone as structures independent of the method.

As shown in cross-sectional view 600 of FIG. 6 , a semiconductorsubstrate 104 is provided. In some embodiments, the semiconductorsubstrate 104 may comprise any type of semiconductor body (e.g.,silicon/CMOS bulk, SiGe, SOI, etc.) such as a semiconductor wafer or oneor more die on a wafer, as well as any other type of semiconductorand/or epitaxial layers formed thereon and/or otherwise associatedtherewith. In some embodiments, a photosensitive layer 105 is formed onthe semiconductor substrate 104. In some embodiments, the photosensitivelayer 105 comprises a material that may change in solubility whenexposed to light having a certain wavelength or within a certain rangeof wavelengths. In some embodiments, the photosensitive layer 105 may beformed by way of, for example, a spin-on process or some otherdeposition process (e.g., physical vapor deposition (PVD), chemicalvapor deposition (CVD), atomic layer deposition (ALD), etc.). Further,in some embodiments, other layers and/or features may be arrangedbetween the photosensitive layer 105 and the semiconductor substrate104, such as, for example, dielectric layers, conductive features (e.g.,wires, vias), transistors, or the like.

As shown in cross-sectional view 700 of FIG. 7 , the semiconductorsubstrate 104 is transported onto a wafer chuck 102 and is arrangedbelow an immersion hood apparatus 106 and a lithography apparatus 118.In some embodiments, the lithography apparatus 118 is laterallysurrounded by the immersion hood apparatus 206 and is arranged directlyover an opening 116 of the immersion hood apparatus 106. In someembodiments, the lithography apparatus 118 comprises a light source 510,a photomask 508, and a first lens 502 arranged directly over the opening116 of the immersion hood apparatus 106. In some embodiments, thelithography apparatus 118 comprises more than one lens, such as, forexample, a second lens 504 and a third lens 506 in addition to the firstlens 502. In some embodiments, the immersion hood apparatus 106comprises input piping 108 and output piping 110 arranged on a lowersurface of the immersion hood apparatus 106 and comprises extractorpiping 112 arranged on outermost sidewalls 106 s of the immersion hoodapparatus 106.

As shown in cross-sectional view 800 of FIG. 8 , in some embodiments,the immersion hood apparatus 106 is turned “ON” such that a liquid 114is injected 802 onto an immersion area of the photosensitive layer 105via the input piping 108 of the immersion hood apparatus 106. In someembodiments, the liquid 114 has a refractive index greater than 1. Insome embodiments, the liquid 114 comprises, for example, water. In someembodiments, the input piping 108 injects 802 the liquid 114 at a rateof between, for example, approximately 1000 milliliters per minute toapproximately 1350 milliliters per minute. In some embodiments, theliquid 114 completely fills a space directly between the photosensitivelayer 105 and a bottommost surface 118 b of the lithography apparatus118 and/or directly between a lowermost lens (i.e., the first lens 502)and the photosensitive layer 105.

Meanwhile, in some embodiments, as the input piping 108 injects 802 theliquid over the photosensitive layer 105, the output piping 110 removes804 any of the liquid 114 that moves away from the input piping 108towards an edge of the semiconductor substrate 104. In such embodiments,the output piping 110 may confine the liquid to the immersion area onthe photosensitive layer 105, as defined by a perimeter of the outputpiping 110. In some embodiments, the output piping 110 removes 804 theliquid 114 at a rate between, for example, approximately 50 millilitersper minute and approximately 100 milliliters per minute. Further, insome embodiments, the input piping 108 and the output piping 110 eachhave a diameter in a range of between, for example, approximately 0.05millimeters and approximately 100 millimeters.

As shown in cross-sectional view 900 of FIG. 9 , in some embodiments,after the liquid 114 is arranged between the first lens 502 and thephotosensitive layer 105 and while the input piping 108 and the outputpiping 110 are continuously injecting 802 and removing 804,respectively, the liquid 114, the light source 510 is turned “ON.” Insome embodiments, when the light source 510 is turned “ON,” light 902 isdirected towards the photomask 508. In some embodiments, the light 902has a wavelength in a range of between, for example, approximately 175nanometers and approximately 200 nanometers. It will be appreciated thatother wavelengths are also within the scope of this disclosure. In someembodiments, only some of the light 902 emitted from the light source510 is able to pass through the photomask 508 based on the solubilitypattern of the photomask 508. Then, in some embodiments, the light 902travels through the first, second, and/or third lenses 502, 504, 506 andalso travels through the liquid 114 to transfer the solubility patternof the photomask 508 to a first area 512 on the photosensitive layer105. Because the light 902 travels through the liquid 114, thesolubility pattern is transferred onto the photosensitive layer 105 at ahigher resolution than if the light 902 traveled through air beforereaching the first area 512.

FIG. 10 illustrates a top-view 1000 of some embodiments of thesemiconductor substrate 104 after the first area 512 is exposed to thelight (902 of FIG. 9 ) according to the photomask (508 of FIG. 9 ).

As shown in the top-view 1000 of FIG. 10 , in some embodiments, thefirst area 512 is only a small portion of the total area of thephotosensitive layer 105. In some such embodiments, the steps of theimmersion lithography process illustrated in FIGS. 8 and/or 9 may berepeated many times to transfer the solubility pattern of the photomask(508 of FIG. 9 ) to the total area of the photosensitive layer 105.

As shown in cross-sectional view 1100A of FIG. 11A, in some embodiments,the wafer chuck 102 is moved 1102 such that a new area of thephotosensitive layer 105 may be exposed to the solubility pattern of thephotomask 508 by the immersion lithography process. In some embodiments,the wafer chuck 102 is configured to securely hold onto thesemiconductor substrate 104 and thus, the photosensitive layer 105 asthe wafer chuck 102 is moved 1102. In some embodiments, the immersionhood apparatus 106 and the lithography apparatus 118 remain stationarywhile the wafer chuck 102 moves.

As the wafer chuck 102 moves 1102, the input and output piping 108, 110continue to inject 802 and remove 804, respectively, the liquid 114 toconfine the liquid 114 within the immersion area defined by theperimeter of the output piping 110. However, in some embodiments, someof the liquid 114 inevitably escapes from the immersion area, and thus,residual liquid 1104 escape to a portion of the photosensitive layer 105that is not directly between the immersion hood apparatus 106 and thewafer chuck 102. In such embodiments, the residual liquid 1104 coulddamage the photosensitive layer 105 and/or future processing steps onthe semiconductor substrate 104.

Thus, in some embodiments, the extractor piping 112 is arranged on theoutermost sidewalls 106 s of the immersion hood apparatus 106 to removeresidual liquid 1104 arranged outside of the immersion hood apparatus106 outer perimeter. In some embodiments, the extractor piping 112comprises a lower segment 112L and an upper segment 112U that meet at afirst angle A₁ that is greater than 90 degrees. Further, in someembodiments, the lower segment 112L is arranged at a second angle A₂with respect to a lower surface of the immersion hood apparatus 106. Insome embodiments, the second angle A₂ is between 0 and 90 degrees. Insome embodiments, the lower segment 112L of the extractor piping 112 hasa first diameter d₁, and the upper segment 112U of the extractor piping112 has a second diameter d₂. In some embodiments, the second diameterd₂ is greater than or equal to the first diameter d₁. In someembodiments, the first and second angles A₁, A₂ as well as therelationship between the first and second diameters d₁, d₂ help increasethe exhaust velocity of the extractor piping 112 to increase the rateand effectiveness of removal of the residual liquid 1104.

As shown in cross-sectional view 1100B of FIG. 11B, as or after thewafer chuck 102 is moving 1102, the extractor piping 112 may remove 1106the residual liquid 1104 from the photosensitive layer 105. Thus, insome embodiments, the cross-sectional view 1100A of FIG. 11A illustratesa first time period, and the cross-sectional view 1100B of FIG. 11Billustrates a second time period after the first time period. Theprevious location 1104 p of the residual liquid 1104 is illustrated inFIG. 11B with dotted lines for convenience. In some embodiments, theextractor piping 112 is continuously running or is always “ON” while theinput and output piping 108, 110 are “ON” such that the extractor piping112 may remove any residual liquid 1104 outside of immersion hoodapparatus 106 at any time during the immersion lithography process. Inother embodiments, the extractor piping 112 may be turned “ON” onlywhile the wafer chuck 102 moves 1102.

When the extractor piping 112 is continuously “ON,” even if, in someembodiments, residual liquid 1104 is left behind on the photosensitivelayer 105 during various steps of the immersion lithography process, theextractor piping 112 is arranged on outermost sidewalls 106 s of theimmersion hood apparatus 106 to remove the residual liquid 1104, therebymitigating damage to the photosensitive layer 105 and/or overall devicesformed on or within the semiconductor substrate 104.

As shown in cross-sectional view 1200 of FIG. 12 , in some embodiments,after moving (1102 of FIG. 11B) the wafer chuck 102, the light source510 is again turned “ON” to transfer the solubility pattern from thephotomask 508 to a second area 1202 on the photosensitive layer 105.

FIG. 13 illustrates a top-view 1300 of some embodiments of thesemiconductor substrate 104 after the second area 1202 is exposed to thelight (902 of FIG. 12 ) according to the photomask (508 of FIG. 12 ). Insome embodiments, the second area 1202 may be arranged next to, but notoverlapping, with the first area 512. It will be appreciated that thesize and shape of the first and second areas 512, 1202 from the top-view1300 are an example, and that in other embodiments, the size and shapeof the first and second areas 512, 1202 may be different than what isillustrated in the top-view 1300 of FIG. 13 .

FIG. 14 illustrates a top-view 1400 of some embodiments of thephotosensitive layer 105 after the immersion lithography process ofFIGS. 8-12 , for example, is repeated over the total area of thephotosensitive layer 105. In some embodiments, the total area of thephotosensitive layer 105 may be defined as the surface area of the topsurface of the photosensitive layer 105. In some such embodiments, thesolubility pattern of the photomask (508 of FIG. 12 ) may be transferredto multiple areas (e.g., the first area 512, the second area 1202) ofthe photosensitive layer 105 such that the total area of thephotosensitive layer 105 comprises soluble regions and insolubleregions. In some other embodiments, the immersion lithography processmay only be repeated over part of the total area of the photosensitivelayer 105.

As shown in cross-sectional view 1500 of FIG. 15 , in some embodiments,soluble regions of the photosensitive layer (105 of FIG. 14 ) areremoved by a developer or wet etchant such that a patternedphotosensitive layer 1502 is arranged over the semiconductor substrate104. In some embodiments, features of the patterned photosensitive layer1502 may a first width w₁ that is in a range of between, for example,approximately 1 nanometer and approximately 45 nanometers. Similarly, insome embodiments, the features of the patterned photosensitive layer1502 may be spaced apart by a first space distance s₁. In someembodiments, the first space distance s₁ may also be in a range ofbetween, for example, approximately 1 nanometer and approximately 45nanometers. Accordingly, in some embodiments, the features of thepatterned photosensitive layer 1502 may have a first pitch p₁ in a rangeof between, for example, approximately 2 nanometers and approximately 90nanometers. It will be appreciated that other values for the first widthw₁, the first space distance s₁, and the first pitch p₁ are also withinthe scope of this disclosure. Further, it will be appreciated that insome embodiments, the method may continue with portions of thesemiconductor substrate 104 and/or layers between the semiconductorsubstrate 104 and the patterned photosensitive layer 1502 being removedaccording to the patterned photosensitive layer 1502 and with depositionprocesses performed to form one or more semiconductor devices on orwithin the semiconductor substrate 104.

Because of the extractor piping utilized in the immersion lithographyprocess, features and/or spacing between the features of thesemiconductor devices may be relatively small (e.g., less than about 45nanometers) and damage to such small semiconductor devices is mitigated.

FIG. 16 illustrates a flow diagram of some embodiments of a method 1600of performing an immersion lithography process using extractor piping toreduce damage by liquid left behind on a semiconductor substrate fromthe immersion lithography process.

While method 1600 is illustrated and described below as a series of actsor events, it will be appreciated that the illustrated ordering of suchacts or events are not to be interpreted in a limiting sense. Forexample, some acts may occur in different orders and/or concurrentlywith other acts or events apart from those illustrated and/or describedherein. In addition, not all illustrated acts may be required toimplement one or more aspects or embodiments of the description herein.Further, one or more of the acts depicted herein may be carried out inone or more separate acts and/or phases.

At act 1602, a photosensitive layer is formed over a semiconductorsubstrate. FIG. 6 illustrates cross-sectional view 600 of someembodiments that may correspond to act 1602.

At act 1604, the semiconductor substrate is loaded onto a wafer chuck,wherein an immersion hood apparatus directly overlies the semiconductorsubstrate, and wherein a light source, photomask, and lens are arrangeddirectly over the semiconductor substrate and within an opening of theimmersion hood apparatus. FIG. 7 illustrates cross-sectional view 700 ofsome embodiments that may correspond to act 1604.

At act 1606, a liquid is applied over the semiconductor substrate anddirectly under the opening in the immersion hood apparatus and lens byusing input piping of the immersion hood apparatus.

At act 1608, output piping of the immersion hood apparatus is used toconfine the liquid to an immersion area arranged directly between theopening and the semiconductor substrate. FIG. 8 illustratescross-sectional view 800 of some embodiments that may correspond to acts1606 and 1608.

At act 1610, a light source is used to apply light through thephotomask, the lens, the liquid, and the photosensitive layer to changethe solubility of portions of a first area of the photosensitive layer.FIG. 9 illustrates cross-sectional view 900 of some embodiments that maycorrespond to act 1610.

At act 1612, the wafer chuck is moved, wherein exhaust piping on outersidewalls of the immersion hood apparatus removes any residual liquidthat escapes from the immersion area during the moving of the waferchuck. FIGS. 11A and 11B illustrate cross-sectional views 1100A and1100B, respectively, of some embodiments that may correspond to act1612.

At act 1614, the light source is used to apply light through thephotomask, the lens, the liquid, and the photosensitive layer to changethe solubility of portions of a second area of the photosensitive layer.FIG. 12 illustrates cross-sectional view 1200 of some embodiments thatmay correspond to act 1614.

Therefore, the present disclosure relates to a method of performing animmersion lithography process over a semiconductor substrate, wherein animmersion hood apparatus comprises extractor piping on outer sidewallsof the immersion hood apparatus to remove any residual liquid thatescapes from the immersion hood apparatus and thus, to mitigate damageto devices formed on or within the semiconductor substrate.

Accordingly, in some embodiments, the present disclosure relates to aprocess tool, comprising: a lithography apparatus arranged over a waferchuck and comprising: a photomask arranged over the wafer chuck, a lightsource arranged over the photomask, and a lens arranged between thephotomask and the wafer chuck; and an immersion hood apparatus arrangedover the wafer chuck and laterally around the lithography apparatus,wherein the immersion hood apparatus comprises: input piping arranged ona lower surface of the immersion hood apparatus and configured todistribute a liquid between the lens and the wafer chuck, output pipingarranged on the lower surface of the immersion hood apparatus andconfigured to contain the liquid arranged between the lens and the waferchuck, and extractor piping arranged on an outer sidewall of theimmersion hood apparatus and configured to remove any liquid above thewafer chuck that is outside of the immersion hood apparatus.

In other embodiments, the present disclosure relates to a process toolcomprising: a wafer chuck configured to hold a semiconductor substrate;a lens arranged over the wafer chuck; a light source arranged over thelens; and an immersion hood apparatus arranged over the wafer chuck,wherein the lens is laterally surrounded by the immersion hoodapparatus, and wherein the immersion hood apparatus comprises: inputpiping arranged on a lower surface of the immersion hood apparatus andconfigured to distribute a liquid between the lower surface of theimmersion hood apparatus and the wafer chuck and between the lens andthe wafer chuck, output piping arranged on the lower surface of theimmersion hood and configured to contain the liquid arranged between theimmersion hood apparatus and the wafer chuck, wherein the output pipinglaterally surrounds the input piping, and extractor piping arranged on asidewall of the immersion hood apparatus and configured to removeresidual liquid outside of an area of the semiconductor substrate thatunderlies the immersion hood apparatus and the lens, wherein theextractor piping is farther from the lens than the output piping.

In yet other embodiments, the present disclosure relates to a methodcomprising: forming a photosensitive layer over a semiconductorsubstrate; loading the semiconductor substrate onto a wafer chuck,wherein an immersion hood apparatus overlies the semiconductorsubstrate, and wherein a light source, photomask, and lens are arrangedover the semiconductor substrate and an opening in the immersion hoodapparatus; using input piping of the immersion hood apparatus to apply aliquid over the semiconductor substrate and directly underlying theopening in the immersion hood apparatus and the lens; using outputpiping of the immersion hood such that the liquid is confined to animmersion area directly between the opening and the semiconductorsubstrate; using the light source to apply light through the photomask,the lens, the liquid, and the photosensitive layer to change thesolubility of portions of a first area of the photosensitive layeraccording to the photomask; moving the wafer chuck; and using the lightsource to apply light through the photomask, the lens, the liquid, andthe photosensitive layer to change the solubility of portions of asecond area of the photosensitive layer according to the photomask,wherein exhaust piping arranged on outer sidewalls of the immersion hoodapparatus removes any residual liquid that escaped from the immersionarea when the wafer chuck moved.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A process tool, comprising: a lithographyapparatus arranged over a wafer chuck and comprising: a photomaskarranged over the wafer chuck, a light source arranged over thephotomask, and a lens arranged between the photomask and the waferchuck; and an immersion hood apparatus arranged over the wafer chuck andlaterally around the lithography apparatus, wherein the immersion hoodapparatus comprises: input piping arranged on a lower surface of theimmersion hood apparatus and configured to distribute a liquid betweenthe lens and the wafer chuck, output piping arranged on the lowersurface of the immersion hood apparatus and configured to contain theliquid arranged between the lens and the wafer chuck, and extractorpiping arranged on an outer sidewall of the immersion hood apparatus andconfigured to remove any liquid above the wafer chuck that is outside ofthe immersion hood apparatus, wherein the extractor piping extends intothe immersion hood apparatus from the outer sidewall and is covered byan upper portion of the immersion hood apparatus.
 2. The process tool ofclaim 1, wherein the extractor piping comprises: a lower segmentarranged at an acute angle with respect to the lower surface of theimmersion hood apparatus; and an upper segment coupled to the lowersegment and arranged at a right angle with respect to the lower surfaceof the immersion hood apparatus.
 3. The process tool of claim 2, whereinthe lower segment meets the upper segment at an angle greater than 90degrees.
 4. The process tool of claim 3, wherein the lower segment has afirst diameter, and wherein the upper segment has a second diameter, andwherein the second diameter is greater than or equal to the firstdiameter.
 5. The process tool of claim 3, wherein pressure in the uppersegment of the extractor piping is less than pressure in the lowersegment of the extractor piping.
 6. The process tool of claim 1, whereinthe extractor piping has a continuous opening on the outer sidewall ofthe immersion hood apparatus.
 7. The process tool of claim 1, whereinthe extractor piping has multiple discrete openings on the outersidewall of the immersion hood apparatus, and wherein the multiplediscrete openings border on a common side of the immersion hoodapparatus and are spaced from each other.
 8. A process tool comprising:a wafer chuck configured to hold a semiconductor substrate; a lensarranged over the wafer chuck; a light source arranged over the lens;and an immersion hood apparatus arranged over the wafer chuck, whereinthe lens is laterally surrounded by the immersion hood apparatus, andwherein the immersion hood apparatus comprises: input piping arranged ona lower surface of the immersion hood apparatus and configured todistribute a liquid between the lower surface of the immersion hoodapparatus and the wafer chuck and between the lens and the wafer chuck,output piping arranged on the lower surface of the immersion hoodapparatus and configured to contain the liquid arranged between theimmersion hood apparatus and the wafer chuck, wherein the output pipinglaterally surrounds the input piping, and extractor piping arranged on asidewall of the immersion hood apparatus and configured to removeresidual liquid outside of an area of the semiconductor substrate thatunderlies the immersion hood apparatus and the lens, wherein theextractor piping is farther from the lens than the output piping;wherein the immersion hood apparatus comprises the sidewall and a secondsidewall facing opposite directions and separated by a width of theimmersion hood apparatus, and wherein the extractor piping extends intothe immersion hood apparatus at a bottom corner of the sidewall and isconfigured to attract and remove the residual liquid outside of thearea.
 9. The process tool of claim 8, wherein the wafer chuck isconfigured to move while the immersion hood apparatus and the lensremain stationary.
 10. The process tool of claim 8, wherein theextractor piping comprises multiple pipes on the sidewall of theimmersion hood apparatus.
 11. The process tool of claim 10, wherein eachpipe of the extractor piping has a lower segment arranged at an acuteangle with respect to the lower surface of the immersion hood apparatus.12. The process tool of claim 11, wherein each pipe of the extractorpiping has an upper segment that is substantially normal to the lowersurface of the immersion hood apparatus.
 13. The process tool of claim8, wherein the extractor piping has a diameter that varies throughoutits length.
 14. A method comprising: forming a photosensitive layer overa semiconductor substrate; loading the semiconductor substrate onto awafer chuck, wherein an immersion hood apparatus overlies thesemiconductor substrate, and wherein a light source, a photomask, and alens are arranged over the semiconductor substrate and an opening in theimmersion hood apparatus; using input piping of the immersion hoodapparatus to apply a liquid over the semiconductor substrate anddirectly underlying the opening in the immersion hood apparatus and thelens; using output piping of the immersion hood apparatus such that theliquid is confined to an immersion area directly between the opening andthe semiconductor substrate; using the light source to apply lightthrough the photomask, the lens, the liquid, and the photosensitivelayer to change a solubility of portions of a first area of thephotosensitive layer according to the photomask; moving the wafer chuck;and using the light source to apply light through the photomask, thelens, the liquid, and the photosensitive layer to change a solubility ofportions of a second area of the photosensitive layer according to thephotomask, wherein residual liquid escapes from the immersion area andbecomes uncovered by the immersion hood apparatus during the moving,wherein exhaust piping arranged on outer sidewalls of the immersion hoodapparatus attracts and removes the residual liquid that escaped, whereinthe exhaust piping has a pair of exhaust piping segments respectively onopposite sides of the immersion hood apparatus, wherein the exhaustpiping segments extend into the immersion hood apparatus respectivelyfrom edges of a bottom surface of the immersion hood apparatus, andwherein the exhaust piping segments extend laterally towards each other.15. The method of claim 14, wherein the liquid has a refractive indexgreater than one.
 16. The method of claim 14, further comprising:developing the photosensitive layer to remove soluble portions of thephotosensitive layer to form a patterned photosensitive layer comprisingopenings.
 17. The process tool of claim 1, wherein an inner sidewall ofthe immersion hood apparatus in the extractor piping is arrangededge-to-edge with the lower surface of the immersion hood apparatus, andwherein an edge-to-edge interface between the inner sidewall and thelower surface is directly under the outer sidewall of the immersion hoodapparatus.
 18. The process tool of claim 8, wherein the immersion hoodapparatus has a pair of inner sidewalls in the extractor piping andextending in parallel into an interior of the immersion hood apparatus,and wherein a first inner sidewall of the inner sidewalls extends fromthe bottom corner.
 19. The process tool of claim 1, wherein theextractor piping has a pair of extractor piping segments respectively onopposite sides of the immersion hood apparatus, wherein the extractorpiping segments extend into the immersion hood apparatus respectivelyfrom edges of the lower surface of the immersion hood apparatus, andwherein the extractor piping segments extend laterally towards eachother.
 20. The process tool of claim 8, wherein the extractor piping iscovered by an upper portion of the immersion hood apparatus.